// vim: set et sw=4 ts=4 sts=4 fdm=marker ff=unix fenc=utf8 nobomb:
/**
 * JavaScript printf/sprintf functions.
 *
 * This code is unrestricted: you are free to use it however you like.
 * 
 * The functions should work as expected, performing left or right alignment,
 * truncating strings, outputting numbers with a required precision etc.
 *
 * For complex cases, these functions follow the Perl implementations of
 * (s)printf, allowing arguments to be passed out-of-order, and to set the
 * precision or length of the output based on arguments instead of fixed
 * numbers.
 *
 * See http://perldoc.perl.org/functions/sprintf.html for more information.
 *
 * Implemented:
 * - zero and space-padding
 * - right and left-alignment,
 * - base X prefix (binary, octal and hex)
 * - positive number prefix
 * - (minimum) width
 * - precision / truncation / maximum width
 * - out of order arguments
 *
 * Not implemented (yet):
 * - vector flag
 * - size (bytes, words, long-words etc.)
 * 
 * Will not implement:
 * - %n or %p (no pass-by-reference in JavaScript)
 *
 * @version 2007.04.27
 * @author Ash Searle
 *
 * -- Split --
 *
 * @version 2009.06.18
 * @author mingcheng<i.feelinglucky[at]gmail.com>
 * @change
 *     [+]new feature  [*]improvement  [!]change  [x]bug fix
 *
 * [*] 2009-06-14
 *      使用闭包改进 sprintf 函数
 *      重写 printf 函数，避免使用 eval
 */

window.sprintf = (function() {
    var pad = function(str, len, chr, leftJustify) {
        var padding = (str.length >= len) ? '' : Array(1 + len - str.length >>> 0).join(chr);
        return leftJustify ? str + padding : padding + str;
    }

    var justify = function(value, prefix, leftJustify, minWidth, zeroPad) {
        var diff = minWidth - value.length;
        if (diff > 0) {
            if (leftJustify || !zeroPad) {
                value = pad(value, minWidth, ' ', leftJustify);
            } else {
                value = value.slice(0, prefix.length) + pad('', diff, '0', true) + value.slice(prefix.length);
            }
        }
        return value;
    }

    var formatBaseX = function (value, base, prefix, leftJustify, minWidth, precision, zeroPad) {
        // Note: casts negative numbers to positive ones
        var number = value >>> 0;
        prefix = prefix && number && {'2': '0b', '8': '0', '16': '0x'}[base] || '';
        value = prefix + pad(number.toString(base), precision || 0, '0', false);
        return justify(value, prefix, leftJustify, minWidth, zeroPad);
    }

    var formatString = function (value, leftJustify, minWidth, precision, zeroPad) {
        if (precision != null) {
            value = value.slice(0, precision);
        }
        return justify(value, '', leftJustify, minWidth, zeroPad);
    }

    var regex = /%%|%(\d+\$)?([-+#0 ]*)(\*\d+\$|\*|\d+)?(\.(\*\d+\$|\*|\d+))?([scboxXuidfegEG])/g;

    return function() {
        var a = arguments, i = 0, format = a[i++];
        return format.replace(regex, function(substring, valueIndex, flags, minWidth, _, precision, type) {
            if (substring == '%%') return '%';

            // parse flags
            var leftJustify = false, positivePrefix = '', zeroPad = false, prefixBaseX = false;
            for (var j = 0; flags && j < flags.length; j++) {
                switch (flags.charAt(j)) {
                    case ' ': positivePrefix = ' '; break;
                    case '+': positivePrefix = '+'; break;
                    case '-': leftJustify = true; break;
                    case '0': zeroPad = true; break;
                    case '#': prefixBaseX = true; break;
                }
            }

            // parameters may be null, undefined, empty-string or real valued
            // we want to ignore null, undefined and empty-string values

            if (!minWidth) {
                minWidth = 0;
            } else if (minWidth == '*') {
                minWidth = +a[i++];
            } else if (minWidth.charAt(0) == '*') {
                minWidth = +a[minWidth.slice(1, -1)];
            } else {
                minWidth = +minWidth;
            }

            // Note: undocumented perl feature:
            if (minWidth < 0) {
                minWidth = -minWidth;
                leftJustify = true;
            }

            if (!isFinite(minWidth)) {
                throw new Error('sprintf: (minimum-)width must be finite');
            }

            if (!precision) {
                precision = 'fFeE'.indexOf(type) > -1 ? 6 : (type == 'd') ? 0 : void(0);
            } else if (precision == '*') {
                precision = +a[i++];
            } else if (precision.charAt(0) == '*') {
                precision = +a[precision.slice(1, -1)];
            } else {
                precision = +precision;
            }

            // grab value using valueIndex if required?
            var value = valueIndex ? a[valueIndex.slice(0, -1)] : a[i++];

            switch (type) {
                case 's': return formatString(String(value), leftJustify, minWidth, precision, zeroPad);
                case 'c': return formatString(String.fromCharCode(+value), leftJustify, minWidth, precision, zeroPad);
                case 'b': return formatBaseX(value, 2, prefixBaseX, leftJustify, minWidth, precision, zeroPad);
                case 'o': return formatBaseX(value, 8, prefixBaseX, leftJustify, minWidth, precision, zeroPad);
                case 'x': return formatBaseX(value, 16, prefixBaseX, leftJustify, minWidth, precision, zeroPad);
                case 'X': return formatBaseX(value, 16, prefixBaseX, leftJustify, minWidth, precision, zeroPad).toUpperCase();
                case 'u': return formatBaseX(value, 10, prefixBaseX, leftJustify, minWidth, precision, zeroPad);
                case 'i':
                case 'd': {
                    var number = parseInt(+value);
                    var prefix = number < 0 ? '-' : positivePrefix;
                    value = prefix + pad(String(Math.abs(number)), precision, '0', false);
                    return justify(value, prefix, leftJustify, minWidth, zeroPad);
                }
                case 'e':
                case 'E':
                case 'f':
                case 'F':
                case 'g':
                case 'G':
                {
                    var number = +value;
                    var prefix = number < 0 ? '-' : positivePrefix;
                    var method = ['toExponential', 'toFixed', 'toPrecision']['efg'.indexOf(type.toLowerCase())];
                    var textTransform = ['toString', 'toUpperCase']['eEfFgG'.indexOf(type) % 2];
                    value = prefix + Math.abs(number)[method](precision);
                    return justify(value, prefix, leftJustify, minWidth, zeroPad)[textTransform]();
                }
                default: return substring;
            }
        });
    };
})();


/**
 * Trival printf implementation, probably only useful during page-load.
 * Note: you may as well use "document.write(sprintf(....))" directly
 */
window.printf = function() {
    document.write(sprintf.apply(arguments.callee, Array.prototype.slice.call(arguments)));
}
